Photocomposing machine



July 19, 1955 J. D. PADGETT 2,713,294

PHOTOCOMPOSING MACHINE Filed Feb. 15, 1955 5 Sheets-Sheet l Jay D. Paragaff INVENTOR ATTORNEY y 1955 J. D. PADGETT 2,713,294

PHOTOCOMPOSING MACHINE Filed Feb. 15, 1955 5 Sheets-Sheet 2 day Q Pa/gaff INVENTOR July 19, 1955 J. D. PADGETT PHOTOCOMPOSING MACHINE 5Sheets-Sheet 3 Filed Feb. 15, 1955 INVENTOR M M P a 9 4 July 19, 1955 J.D. PADGETT PHOTOCOMPOSING MACHINE 5 Sheets-Sheet 4 Filed Feb. 15, 1955ATTORNEY numw July 19, 1955 J. D. PADGETT 2,713,294

PHOTOCOMPOSING MACHINE Filed Feb. 15, 1955 5 Sheets-Sheet 5 Jay 0.Padgeff INVENTOR United States Patent Qfhce This invention relates tophotographic printing machines and more particularly to an apparatus forand method of transferring subject matter of a negative to a sensitizedplate.

This application is a continuation-impart of my application SerialNumber 409,499, filed February 10, 1954 for Methods and Means for Maitig Photographic Exposures.

Accuracy in the positioning and aligning of the images to be transferredfrom a negative to the sensitized plate in step and repeat printing hasbeen accomplished in several differ nt ways through the medium chieflyof frames. lJc-vertheless, the trade deer precision in obtaining properregister 1 less t t e consuming labor which is ones because of theabsence of adequate retention of. es once proper registry is attaiied.Prior devices for obtaining alignment of the plates and for retairingalignment thereof include various types of tapes, clamps and the likeattached to the printin frame and which detract from the flexibility ofthe apparatus while seeking to reduce time and skill the preparation ofthe Work for printing.

it is the primary object of the present invention to provide an improvedapparatus for and method of insuring greater accuracy in positioning thenegative or color transparencies 1-. relation to the plate and forholding the negative and plate in any desired position on the deck orbed of the pr ing frame by positioning elements arranged inpredetermined relationship with each other and with said negative andplate and which positioning elements require no fixed means ofattachment to said printing frame.

Another object of the invention is to provide a photographic printingmachine employing a vacuum frame which is composed of a cover frame anda magnet bed of corresponding dimensions, the cover frame being hingedalong its rear edge to the rear edge of the magnet bed, both the coverframe and magnet bed being pivoted for rotation about a horizontal axisextending through the top rnidsection of a cabinet.

Anotl'xer object of the invention is to provide, in a photographicprinting machine, a magnet bed in which permanent bar magnets ofsubstantially U-shape in transverse section are fioatingly assembled inend to end relationship in parallel rows extending preferably diagonallyfrom side to side of the frame embracing the bed which underlies the airimpervious blanket common to most t pes of vacuum frames. The northpoles of the magnets, as are the south poles, are disposed injuxtaposition for repulsion and this feature, combined with the factthat the area covered by the magnets creates a magnetic fieldsubstantially equal in area to the blanket which is devoid of inactivespots.

Another object of the invention is to provide, by virtue of the magneticfield, a medium by which negatives, color transparencies, stencils orthe like may be held on non-ferrous printing plates by ferrous rules,chase or bars with no 'i' another object of the invention is to providea -'el coin. ldlancing means for the transparent cover of he vacuumframe and a safety latch which interlocks the cover and magnet bed invertical position of these a nts to prevent tilting of the cover frameindependently of the magnet bed.

till another object of the invention is to provide stop means forpreventing unlatched condition of the finct at all times during periodsof loading or the cover frame is in raised position and to provide aseor" the stop means in lowered position of the cover rarne.

Still another object of the invention is to provide a masking meansconsisting of spring biased roller curtains of black, light-proofmaterial, each capable of being independently drawn into overlappingrelation to another to overch the operative area of the vacuum frame andsecurable in positions to define the particular area occupied the ativeon the printing plate or film, as the Q56 may be. and thus preventexposure of the plate *eyond that necessary to reproduce the image inthe step and repeat process.

With the foregoing and other objects in view, the invention hasreference to certain salient features of construction and arrangement ofparts which will become manifest a 'ne description proceeds and whichare illustrated in the accompanying drawings, wherein:

Figure l is a front perspective view of a photographic 'ng machineembodying the invention in which the cover frame is shown in raisedposition.

Figure 2 is a View in vertical section, dotted lines the printingposition.

Figure 3 is a rear view 5 the machine in which the printing frame isshown in vertical position.

Figure 4 is a fragmentary perspective view showing one of the clamps forsecuring the masking curtains in adjusted positions.

Figure 5 is a top plan view of the machine with portions of the topcover and blanket broken away to show the magnet bed beneath.

Figure 6 is a fragmentary perspective view showing the air outlet forevacuating the vacuum printing frame.

Figure 7 is a fragmentary sectional view of the printing frame showingthe floating action of the magnets as influenced upwardly by the ruleelements.

Figure 8 is a fragmentary perspective view of the magnet bed.

Figure 9 is a vertical sectional view taken on line 9-9 of Figure 5.

Figure 10 is a vertical sectional view taken on line 1tl-ltl of Figure5.

Figure 11 is a fragmentary net bed.

Figure 12 is a detail view of the safety latch for preventing accidentalrelease of the printing frame from its latched position in the cabinet,and

Figure i3 is 2 fr :5! p front corner of the machine showi of one of themagnet bed latches.

Continuing with a more detailed description of the drawing, referencenumeral 19 denotes generally the cabinet of the printing machine whichis constructed of This showing in frame in vertical or exposing top planview of the magview of no 21g an enlarged detail is to enable themachine to be moved in sections through doors of standard width.

The lower section 12 has a bottom portion 13 set inwardly from the frontof the cabinet to provide toe space for the operator, and verticallyadjustable supporting legs 14 enable the cabinet to be leveled on unevenfloors.

The upper section 11 of the cabinet has a flange 15 (Fig. 2) about itslower edge which abuts a like flange 16 about the upper edge of thelower section 12 and bolts 17 secure these flanges together (Figure 2).The top of the upper section 11 is slightly upwardly inclined rearwardlytoward the rear of the cabinet to afford a more facile Working plane.

Referring to Figure 2, it will be observed that the cabinet 19 has avertical, transversely extending partition 13 which separates the frontcompartment 19 from the rear compartment This partion is in transv selypanels (Figure 3) for ready removal and access to the compartment 19which contains the controlling elements of the printing machine andwhich will be presently described and explained.

The upper edges of the front and sides of the upper section 11 of thecabinet are curved inwardly at 21 (Fig. l) and extending from side toside of the section 11 is a plate 22 (Figure 2) inclined to the sameplane as the top of the cabinet and terminating at the top of the panelsforming the horizontal partition 1%. This plate 22 has side flanges 23(Fig. 2) which extend upwardly and meet with the inturned edges 21 ofthe upper cabinet section 11. The plate 22 is supported on angles 24(Fig. 2) aflixed to each side wall of the cabinet. This plate 22 servesno other purpose than to close the top of the compartment 19 of thecabinet when the printing or vacuum frame, broadly designated byreference numeral 25, (Fig. 5) is tilted to the vertical position, asshown in dotted lines in Figure 2 The printing frame 25 (Fig. 5) iscomposed of the magnet bed generally indicated by reference numeral 26and a cover frame generally indicated by reference numeral 27 (Fig. 2)The magnet bed is composed of a rectangular frame 28 formed of flat,inverted channel members secured to a flat base 29 by screws 2% (Figs. 9and 10). Within the confines of the channel members or sides of theframe 28 is arranged on the bed or base 29 a plurality of diagonal rowsof bar magnets 39 (Figs. 7 and ll) of substantially U-shape intransverse section. Each row of magnets St is separated from another bymeans of spacer bars 1.1) each of which is continuous from side to sideof the magnet frame 28 and is held to the base plate or bed 29 by meansof screws 32 (Fig. 7). The top surfaces of the spacer bars 31 are flushwith each other and with the frame 23 while the common upper plane ofthe magnets an is slightly below that of the spacer bars 3% and theframe 23 (Fig. '7). This permits the magnet 36 to float or moveupwardly. Upward movement of the magnets, as caused by influence offerrous elements thcreabove, is limited by retainer bars 33 (Fig. 7)which lie between the upstanding flanges of the magnets 38! and extendbeyond the ends of each row of magnets and are secured by screws 34 tothe tops of ferrules 35 (Fig. 8), the screws extending through theferrules and threaded into holes in the bed plate 29, which is likewisetrue of the screws 32 which hold down the spacer bars 31.

The magnet bed 2? is suspended on the pivots 46 (Figs. 2 and 5) at apoint slightly forwardly of the center of gravity so that its normaltendency is to move in the direction of the vertical plane.

The magnets are capable of limited lateral and longitudinaldisplacement, restricted by the relative spacing of the spacer bars 31between which the magnets are arranged. The magnets are disposed withtheir north poles in juxtaposition so that one will repulse another andthus insure a complete and unbroken magnetic field throughout the areaof the bed plate 28 covered by the magnets.

The base plate 29 extends beyond the sides and ends of the magnet frame25, as shown in Figures 9 and 10 and to each extended side of the plate29 is secured, by means of screws 36, a flat rail 37. A similar butnarrower rail 33 is secured by means of a screw 39 (Fig. 9) to theextended rear edge of the base plate 29. These rails 37 and 33 form arectangular support for the perimeter of a blanket 44) (Fig. 9) whosesealing flange 41 is longitudinally coextensive with each side rail 37and the end rail 38. Further reference to the blank t 46 will be madepresently.

Mounted on the inclined plate 22 at each rear corner (Figure 2) is amagnet bed hinge bracket 42. Bolts 43 secure this bracket to the plate22. The upper end 44 of this bracket extends through a slot 45 (Figure5) in a block 45:; seated in a recess in each of the two side rails 37on opposite sides of the magnet bed 29. A pivot pin extends throughmatching holes in the upper end of bracket and the bearing block 4511,thereby supporting the printing frame 25 for rotation about an axisthrough the pivot pins 46 from a plane parallel with the inclined top ofthe cabinet l5 into a vertical plane suggested by dotted lines in Figure2.

The air tight cover frame 27 is composed of side flanges 47 of rightangular cross-section (Figure 10) and front and rear flanges 48 (Figure9) of like cross-sectional shape. A glazing frame 49 (Figures 9 and 10)is spaced inwardly from the side and front and rear flanges 4'7 and 43,respectively, and from the top of the frame 27. Such spacing provides anelongated recess or chamber 50 coextensive With each side of the coverframe and a like recess or chamber 53 along the front and rear edges ofthe frame. These recesses are adapted to contain the rollers on whichare wound curtains of light proof material which will be explainedlater.

Mounted on the glazing frame 49 are the edges of a glass panel 52 whichare made air tight with the frame 49 by a suitable sealing medium 53(Figures 9 and 10). The glass panel 52, when the cover frame is loweredinto operative position, is in contiguous engagement with the sealingflange 4-1 of the rubber blanket at The cover frame 27 is joined to themagnet base plate 29 by means of plate hinges 54 (Figure 10), one flangeof each hinge being afiixed by screws to the underside of the rearmember of the glazing frame 49 while the companion flanges of the hinges54- are similarly secured to a rail 55 (Figure 9), secured to theunderside of the magnet base plate 29 along its rear edge. It is evidenttherefore that the cover frame 27 may swing upwardly from the positionshown in solid lines in Figure 2 to the position shown in Figure l, inwhich position the cover frame is counter-balanced by means of a springassembly shown in Figure 9.

The spring assembly for counterbalancing the cover frame 27 consists ofa heavy coil spring 56 contained in a tubular housing 57. A pair ofidentically shaped com pression rods 53 and 59 are employed. Thecompression rod 58 is formed into an elongate U-shape having the endsbent into return hooks Gil which are slidable in diametrically opposed,longitudinal slots originating at one end of the tubular housing 57 asthe spring is brought under compression by lowering the cover frame. Thebight end 61 of the compression rod 58 is attached, by means of a bolt62 to the downwardly and rearwardly extending leg 63 of a bracket 64.The bracket 64 is secured by bolts 65' and as to the under side of theglaz ing frame 4%, as shown in Figures 9 and 10.

The companion compression rod 59 has its legs extending also through thecoil spring 56 in a plane at right angles to that of the compression rod53 and the ends of the compression rod 5@ are bent into books 67 whichare slidable in diametrically opposed slots 68 in the opposite end ofthe tubular housing 57 and engage the end of the spring 56 opposite thehooks fit) of the companion compression rod 53. The bight portion of theU-shaped 5 compression rod 59 is attached to a pin 69 (Figure 2) carriedby a bracket 7% secured on each side of the magnet base 29 adjacent thepivotal pins 4-6 thereof.

The cover frame is counterbalanced by compression of the spring by theoppositely disposed compression rods 58 and 59 and it remains in anyangular position to which it is moved. Maximum compression of the springexists in lowered position of the cover frame and minimum compressionexists when the frame is disposed in its highest position.

In preparing the machine for printing, 21 ca elated rule bar 71,negative holder 2 and a scale bar '73 (Figure 5) are employed. Theseelements are made of steel or other ferrous metal and are preferablyhighly flexible. The initial step of laying out the work may beaccomplished on a light table or other flat surface and transferred tothe blanket in of the machine for al on the sensitized printing plate74. For this reason, scale members 'Fl, 72 and 7'3 are made independentof the machine and, being ferrous, they are strongly attracted by themagnetic field created by the magnet bed over which the work is placedfor printin The first step is to position the negative 75 accuratelywith respect to the scale bar 73 or its equivalent, after which thenegative holder 2, which is simply a thin fiat rectangular strip offerrous metal, is located with respect to the scale bar 73 by means ofthe single line 76 midway of its ends and which is brought into properregister with the calibrations on the scale bar '73. The negative issecured to the negative holder 72 by means of a strip 77 of adhesivematerial which is applied to the undersurface of the negative andnegative holder.

When the printing plate 74*? is positioned on the bla t if the lateralleg 78 of the scale bar '73 is placed against the calibrated edge of therule bar 71 which extends across the printing plate 7 the calibratedmembers 71 and 73 forming a right angle in cases where the step andrepeat process involves work, such as illustrated, where the scalemembers can be positioned in parallelism with the sides and ends of theprinting frame.

it is, of course, desirable in carrying out the process to accuratelylocate the negative 75 in the lower left hand corner of the printingplate 74 for the first exposure and proceed progressively across theplate with successive exposures, after which the exposures are madesuccessively upward, thence downwardly where the next adjacent verticalrows of exposures are made until the entire plate 74 has been exposed,the scale members and negative holder being drawn firmly against theblanket 4% by the magnet bee and will not become displaced from theirfixed positions except by manually lifting them out of the field ofinfluence created by the magnet bed.

When the Work is assembled on the blanket in the manner described or inaccordance with any conventional practice, the cover frame 27 is closed.The switch '79 (Figure 1) which starts the motor Si (Figure 2), isactuated, the motor operating the pump 81 to evacuate the vacuum tank82. A line 83 (Fig. 6) eff ct communication between the ta 32 (Fig. 2)and the s ace formed between the cover frame 25 and blanket by means ofan air outlet 84 (Figures 2 and 6). A vacuum control switch 35 (Figurel) is actuated to open the line 33 to evacuate the air in the spacebetween the cover frame and blanket, whereupon the blanket is forced uwardly by atmospheric pressure and absence of air it said space andbears firmly a let the printing plate 74, the negative and the workholding elements, as exemplified in Figure 7.

As the blanket 49 moves upwardly, the particular magnets 3b whichunderlie the ferrous elements on the blanket, are drawn upwardly bytheir attraction to these elements, there being provided a space betweenthe bases of the magnets and their retaining bars 31 for upward displacement of the magnets a distance substantially equal to the upwarddisplacement of the blanket 4 The magnets other than those influencedupwardly by the ferrous elements remain, of course, at rest.

During loading operations, the magnet base frame is held down by meansof a latch 87 (Figures 2 and 13) which extends upwardly through a slot88 in the plate 22 underlying the magnet base. The latch 37 has a hook39 which engages a large pin 95 affixed to and extending laterallyoutward from a lug or keeper 91, affixed by screws 92 to the magnet baseframe member 37.

By referring to Figure 2, it will be seen that the lower end of thelatch 87 is apertured to receive an end of a longitudinal shaft 93 'chextends from side to side of the cabinet it) immediately behind theinstrument panel 94 which is recessed in the front wall of the cabinet.To this shaft 93 is rotatably connected the rear end 95 of a pull rod. 56 which extends laterally through an opening in the panel and carries apull knob 97 (Figure l). pulling this rod, the shaft 93 is rotated totilt the la. rearwardly and disengage itself from the pin 90 by which itis connected to the magnet bed frame. The pull rod 96 is biased inwardlyby a coil spring as (Figure 2), connected at one end to the lower end ofthe latch 87' and. at its opposite end to upper edge of the plate 22.inc cover frame 25 has a latch 98 (Figures 1 and 2) swingingly suspendedby a pivot pin from each of its front corners. When the magnet base andcover frame are in lowered position, the cover frame is released fromlocked relationship with the magnet base since the small, laterallyextending pin liltl, carried by the latch 8'7, is engaged by the camsurface llll (Figure 2) on the swinging latch )3, causing the latter tomove forwardly, dis engaging itself from the large pin 9% and freeingthe cover frame for independent movement in relation to the magnet base.

When the work has been composed on the blanket as preparatory toexposing to light, the pull 96 is drawn outwardly to disengage latch 87to free the magnet base frame for upward movement, whereupon the coverframe is grasped by the lifting rail along its front edge and is raised.As the cover fran s is moved upwardly, the latch 93 swings by gravityinto locking position with the large pin i l"! on the magnet basethereby locking the cover frame and magnet base together. This isimportant since the cover frame, when the assembly is in verticalposition for exposure, would tilt backwardly away from the magnet baseif the vacuum holding the cover frame and magnet base together shouldfail.

'When the assembly is disposed in the position shown in Figures 1 and 2,the negative and plate or film are exposed to a brig.t light for aduration predetermined by the setting of a timer 163, after which theoperation is repeated until the desired area of the printing plate hasbeen exposed.

Adjacent the timer W3 on the instrument panel 94 is a vacuum gauge 1&4which is in communication with the vacuum tank 82 by means of a tube 1&5(Figure 2).

To avoid any possi lity that the magnet base or frame 29 be releasedfrom its latched position in relation to the cabinet 16 while the coverframe 27 is in raised position, a. latch stop bar 137 (Fig. 12) ispivotally mounted on the under side of one edge of the magnet base framerail 37 as seen in Figure 13, immediately behind the latch 87 to preventits rearward movement should the pull rod 3 6 be accidentally actuated.

The latch stop bar 37 is oscillatably mounted on a pivot pin 333 whichextends through matching holes in the parallel legs :39 of an invertedU-shaped bracket 1% (Fig. 13), secured by screws s ll to the under sideof the magnet frame .il 3?. The forward end of the stop bar 137 isnormally biased downwardly by a coil spring 14-2 interposed between saidforward end and the under side of the magnet frame rail. Extendinglaterally outward from the rear end of the stop bar 137' is a pin 14 3which is engaged by the lower edge of the side flange of the cover frame27, as the latter is lowered, thus to tilt the f8o7rward end of the stopbar upwardly to clear the latch It is evident from the foregoing thatwhen the cover frame 27 is in raised position, the forward end of thestop bar 137 will be compelled by the spring 142 to lie in the path ofthe latch 87, preventing its rearward displacement as effected byoutward movement of the pull rod 96. Thus, the magnet bed cannot befreed for rotation on its pivots until the cover frame is lowered, whichaction brings the lower edge of the side flange of the cover frame intoengagement with the lateral pin 143, rocking the stop bar 137 on itspivot 138 and raising its forward end free of the latch 87. Only thencan the latch 87 be actuated. There is never a need that the magnet basebe raised without its first having been latched to the cover frame sothat I both may move together into vertical position for burning orexposure. Earlier in the description the provision for latching the twoframes together was explained.

I n order that the exposed area of the printing plate 74 may berestricted only to the area thereof covered by the negative, a maskingarrangement is provided which enables an operator to expose the entireworking area of the blanket or restrict the exposure area to any sizeand at any position desired on the printing plate.

The masking arrangement is comprised of a roller 166 journaled at itsends in the ends of each of the compartments or recesses 51 at the frontand rear of the cover frame 27. In like manner, rollers 107 are arrangedin each of the elongate recesses at each side of the cover frame. Woundon each of the rollers 1136, which are constructed in the manner of awindow shade roller, is a curtain 108 of light proof material.

Extending longitudinally across the cover frame 27 is a curtain bar 109(Figure 5), to which is secured the end of the curtain 108 by means of ametal strip 110 which is parallel with the edge of the bar 109 nearestthe roller 106. The curtain passes oif the roller 106 and over thevertical portion 111 of a guide rail 112 (Figure 9) of substantiallyT-shape in transverse section. The upper edge of the vertical portion111 is curved and polished so that the curtain 108 will slide freelythereover as the curtain bar 109 is moved over the cover. The guide rail112 is mounted on the front and rear portions of the glazing frame 49.

The curtain bar 109 is maintained in parallelism with the front and rearsides of'the frame by means of spools 113 (Figure 10) rotatable on pins114 on the under side of mountings 115 which are formed by breaking theends of the curtain bars 109 upwardly and outwardly as revealed inFigure 10. The annular grooves of the spools 113 receive the inner edgesof a track 116 which is afiixed to the horizontal portion 117 of theflange 47 of the cover frame 27.

The curtains 108 which are drawn from the front and rear rollers 166 andtheir associated elements, as described, are identical, hence adescription of the companion or front curtain is unnecessary. Each ofthe curtain bars 109 has a curtain pull or operating handle in the formof a vertical rail 118 which extends upwardly from the bar and islongitudinally coextensive therewith.

The side curtains 119 (Figure 10) are each drawn from a roller 107 andtravel over a guide rail 120 of substantially L-shape in transversesection and whose vertical leg is secured to the glazing frame 49 alongeach end thereof. It is noted that the curtains of the rollers 107travel under the curtains of the rollers 106, hence the guide rails 120are on a lower plane than the guide rails 112.

To the end of each of the curtains 119 is secured by means of a strip121a, a curtain bar 121 (Figures 1 and 10) which extends from front torear of the cover frame 27, and at each end, the bar 121 is brokenupwardly and again into parallelism with the plane of the bar to form amounting 122 carrying a pair of spools 123, mounted on pins 124. Thegrooves of the spools receive tracks o, u 125, afiixed to andcoextensive with the glazing frame 49 along its front and rear sides, asshown in Figure 9.

It is evident from the foregoing that each curtain can be operatedindependently of the other three, hence the confronting edges of thebars of the curtains can be moved relative to each other to define anexposure area of any dimensions and at any selected point throughout theentire operative area of the printing frame. It is necessary howeverthat since the curtains are all normally biased toward their respectiverollers, means must be provided for securing the curtains in theiradjusted positions.

The securing means for the curtains is shown in detail in Figure 4 andconsists of a block 126 which is of substantially L-shape in transversesection to form a longitudinal leg 127 shorter than the block 126 andwhich is slidably disposed on one side of a strip 128 which is afiixedto and coextensive with the curtain bar 121 of a curtain 119 andparallel with the securing strip 121a, as more clearly shown in Figure3. The block 126 is slidably disposed on the top of the strip 128 andhas a plate 129 secured by screws 130 to its side opposite the leg 127.The plate 129 is cut away at 131 and has a right angular lip 132 formedon its lower edge which extends under the strip 12%. The block 126 has adownwardly extending lip 133 formed on its end above the cut-awayportion 131 of the side plate 129 and this lip, cut-away portion 131 andthe block 126 combine to form a rectangular passage for a strip 134which is secured to the curtain bar 169 opposite the strip 110 whichsecures the curtain to the bar.

From the foregoing, it is made apparent that the strip 128 of thecurtain bar 121 is capable of longitudinal sliding movement between theblock 126, its side leg 127 and the opposite side plate 129. In likemanner, the strip 134 of the curtain bar 169 is capable of slidingtransversely with respect to the strip 128. Therefore, the four curtainsmay be moved independently to define any sized opening at any point overthe work surface.

To secure the blocks or curtain holders 126 in adjusted positions, ascrew 135 is threaded through the block adjacent one end and bearsagainst a wear plate 136 which, in turn, bears against the strip 134.Since the right angular lip 132 of the side plate 129 engages the underside of the strip 128 traversing the strip 134 and its curtain bar 1 13,tightening of the screw 135 will draw the members into clampedrelationship. In this manner, the four curtains are held in adjustedpositions, so that when the printing frame is disposed vertically forexposure to light, such exposure will be restricted to the openingdefined by the positioning of the curtains.

Referring again to the magnet base of which it was mentioned earlierthat the parallel rows of magnets 30 were disposed diagonally across thebed; it is pointed out that insofar as performance is concerned, therows of magnets may just as well extend parallel with the sides or endsof the bed but for practical reasons the diagonal disposition of therows of magnets is preferred. If the rows of magnets were parallel withthe long axis of the work surface which is the plane in which most ofthe Work is laid out, the magnetic flux may not be as pronounced betweenthe rows of magnets and it is possible that one of the scale members maybe placed so that a major portion thereof will be between the paths ofmagnetic force and hence will not be as firmly held as they would be ifthe rows of magnets are arranged diagonally. Moreover, such diagonalarrangement of the rows of magnets is found to more evenly distributethe influence of the magnets through the steel composing elements.

It is further mentioned that while the masking arrangement is shown anddescribed as overlying the glass in the cover frame, it is evident thatwithout material change, the masking arrangement can be interposedbetween the glass and the blanket 4i Manifestly, the construction asshown and described is capable of some modification and suchmodification as may be construed to fall within the scope and meaning ofthe appended claims is also considered to be within the spirit andintent of the invention.

What is claimed is:

1. In a photocomposing machine, a cabinet, 21 rectangular printing framemounted in said cabinet for rotation about an axis through itslongitudinal midsection, said printing frame consisting of a magnet bedframe and a cover frame hinged to said magnet bed frame along its rearedge and having a transparent air tight top, a magnet bed in said magnetbed frame, a non-porous blanket overlying said magnet bed on which isadapted to be disposed a sensitized printing plate, a ferrous negativeholder and scale members having registerable scale lines for orienting anegative in said holder in relation to said printing plate andmaintaining the position of said negative and printing plate through manetic attraction of said holder and scale members to said ma net bed,magnets in said magnet bed frame movable towards and from said coverframe by influence of said ferrous negative holder and scale members,and means for exhausting air from between said cover frame and magnetbed frame.

2. In a photocomposing machine, a printing frame comprising a tiltablemagnet bed frame and a cover frame hinged to said magnet bed frame forindependent movement and having a transparent top, marginal sealingmeans between said magnet bed frame and said cover frame, a plurality ofrows of magnets in said magnet bed frame movable towards and from saidcover frame and creating a magnetic field coextensive with the inneredges of said magnet bed frame, a non )OfOUS blanket disposed on saidmagnets defining a working area, a printing plate freely mounted on saidblanket, elongate scale members of ferrous material attracted to saidmagnetic field throughout their lengths, one of said scale members beingdisposed at the margin of said plate and the second of said members beinslidable over said plate along the first member and extendingtransversely from said first member, a ferrous negative holder retainedby said magnetic field and coordinating with said second member toeifect registration of a negative with said printing plate, means forsecuring said magnet bed frame and said cover frame in sealingrelationship and means for exhausting air from between said framespreparatory to exposing said negative to light.

3. The structure of claim 2, and a curtain roller parallel with eachside and end of said cover frame, each carrying a curtain adapted to bedrawn independently of the other curtains over the transparent top ofsaid cover frame, guide means for each of said curtains and means forsecurirn said curtains in drawn position to define an exposure area ofany size and at any selected position throughout the working area ofsaid blanket.

4. in a photocomposing machine, apparatus for obtaining accurateregister of a negative on a printing plate comprising, in combinationwith a printing frame, a magnet bed defining a magnetic fieldcoextensive with the working area of said printing frame, a rubberblanket overlying said magnetic field on which said printing plate ispositioned, a light transmitting cover plate included in said printingframe; a first substantially thin, elongate scale bar of ferrous metalin parallelism with one edge of said plate, a second elongate scale barslidable over said plate in register with scale lines on said firstscale bar, a negative holder of ferrous material adapted to registerwith the scale lines of said second bar, said scale bars and negativeholder being maintained in registering position by said magnetic fieldduring and after orientation of said negative on said plate, said magnetbed frame including a plurality of magnets movable towards or from thecover plate by influence of said ferrous scale bars and negative holder;and means for evacuating said printing plate of air preparatory toexposing said negative and underlying negative to light.

5. In combination with the printing frame of a photocomposing machine,apparatus for accurately positioning a negative on a printing platecomprising a magnet bed producing a magnetic field coextensive with theWorking area of said printing frame, said printing frame including alight transmitting cover; a blanket overlying said magnet bed on whichsaid printing plate is positioned, said magnet bed frame including aplurality of magnets movable towards or from the cover; a firstcalibrated means of ferrous metal parallel with one edge of said plate,analogous calibrated means perpendicular with said first calibratedmeans adapted for sliding adjustment over said plate in relation tocalibrations on said first calibrated means, a negative holder offerrous material adapted to register with calibrations on said analogouscalibrated means to orient said negative in relation to said plate, saidcalibrated means and negative holder maintaining predisposed positionsof said negative and plate under the influence of said magnetic fieldWhile said negative and the underlying area of said plate are exposed tolight.

6. The structure of claim 5, said magnet bed comprising a frame andparallel rows of magnets extending diagonally across said frame in endto end relationship.

7. The structure of claim 6 wherein the north and south poles of saidmagnets are reversed, one with respect to another to repulse each otherboth longitudinally and laterally to create an unbroken magnetic field.

S. In combination with the printing frame of a photocomposing machine, amagnet frame in said printing frame, said printing frame including alight transmitting cover; parallel rows of magnets occupying said magnetframe to create a magnetic field, a blanket covering said magnets meansfor registering a negative with light sensitive printing plate on saidblanket comprising a substantially fiat ferrous holder for saidnegative, said magnet frame including a plurality of magnets movabletowards or from the said cover; a pair of flat, elongate scale elementsdisposable in relation to each other and to said negative holder andinfluenced by said magnetic field into intimate contact with saidblanket and portions of said printing plate and effective to orient saidnegative in relation to said printing plate and to maintain predisposedrelationship of said negative and plate during exposure thereof tolight.

9. The structure of claim 8, wherein said rows of magnets are arrangeddiagonally in relation to said frame.

10. The structure of claim 9 wherein the north and south poles of eachmagnet are opposed to corresponding poles of adjacent magnets forrepulsion of the magnets with respect to each other to create anunbroken magnetic field.

References Qited in the file of this patent UNITED STATES PATENTS1,813,689 Weisker July 7, 1931 2,129,768 Huebner Sept. 13, 19382,259,238 Bernhard Oct. 14, 1944 2,587,084 Anderson Feb. 26, 1952FOREIGN PATENTS 22,112 Great Britain Oct. 10, 1902 540,700 Great BritainOct. 27, 1941

